Generally, a secondary battery includes a positive electrode including a positive electrode active material and a positive electrode current collector, a negative electrode including a negative electrode active material and a negative electrode current collector, and a separator interposed between the positive electrode and the negative electrode, where a electrolyte solution is impregnated into the negative electrode, the positive electrode, and the separator and functions as an ion passage. A lithium secondary batteries, which has recently been popular as a small-sized or medium and large-sized power source, uses an organic electrolyte solution as an electrolyte solution. The organic electrolyte solution exhibits a high electromotive force, which is twice or more times higher than that of a conventional battery using an aqueous alkaline solution. As a result, a lithium secondary battery exhibits a high-energy density.
However, as the stability of an organic electrolyte in the lithium secondary battery has been recently questioned, a solid electrolyte for replacing an organic electrolytic solution is being highlighted. In order for the solid electrolyte to exhibit electrical insulation and high ion conductivity, uniform gelation or solidification of an electrolyte during manufacturing process of a secondary battery and wettability between the electrolyte and an active material are important.
The gelation or solidification of the electrolyte is usually performed through a high temperature heat treatment. In this case, a polymer electrolyte may be easily deteriorated due to a high temperature. When a low temperature process is performed to suppress deterioration, the overall process time increases as well as an electrolyte is not uniformly gelated or solidified. Furthermore, when an electrolyte is not uniformly gelated or solidified, the wettability between the electrolyte and an active material is poor, and thus capacity of a battery is lowered.